JPH11323365A - Hydraulic oil - Google Patents

Abstract

[PROBLEMS] To provide excellent oxidation stability, extreme pressure properties, sludge generation suppression properties, and sludge resistance, and maintain these properties over a long period of time even under high-temperature and high-pressure conditions of an actual piston pump. To provide hydraulic fluid. SOLUTION: This is a hydraulic oil based on a mineral oil or a synthetic oil or a mixed oil thereof, wherein (A) alkenyl succinimide or a derivative thereof is present in an amount of 0.01 to 1 relative to the total mass of the hydraulic oil. % By mass, and (B) phosphate ester is 0.1%
1 to 5% by mass, (C) 0.05 to 0.5% by mass of alkylated diphenylamine, and (D) 0.05 to 0.5% by mass of hindered phenols.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic fluid, and more particularly, it shows excellent oxidation stability, extreme pressure, sludge generation suppression and sludge resistance even under high temperature and high pressure conditions of an actual piston pump. In addition, the present invention relates to a hydraulic fluid capable of maintaining these characteristics for a long period of time.

[0002]

[Background of the Invention] Generally, lubricating oils such as hydraulic oils, which emphasize oxidation stability and lubricity, include mineral oil base oil, antioxidants and extreme pressure agents, rust inhibitors, defoamers, etc. Of various additives are used.

[0003] Above all, abrasion-resistant hydraulic fluids include zinc dithiophosphate (Zn) having both lubricating performance and antioxidant function.
DTP) is used. But Z
While nDTP has both excellent lubricating performance and antioxidant function, it has a slightly low heat resistance and may be thermally decomposed when subjected to a thermal load to form sludge.

Therefore, in a device to which a thermal load is applied, instead of such a zinc-based hydraulic oil, a phosphorus-based or sulfur-based extreme pressure agent having lubrication performance equivalent to that of the zinc-based hydraulic oil is used. Ashless abrasion resistant hydraulic fluid is used. However, in recent years, miniaturization of tanks in hydraulic devices,
Due to high efficiency such as high output, high pressure, and high speed control, the thermal load on hydraulic fluid has been further increased. Therefore, sludge is easily generated.

[0005]

The object of the present invention is to provide excellent oxidation stability, extreme pressure properties, suppression of sludge generation, and sludge resistance (even if some sludge is generated, even under the above-mentioned high-temperature and high-pressure use conditions). It is an object of the present invention to provide a hydraulic oil capable of exhibiting the above properties and maintaining these properties for a long period of time.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the hydraulic fluid of the present invention is a hydraulic fluid based on mineral oil or synthetic oil or a mixed oil of the two, and based on the total mass of the hydraulic oil. , (A) 0.01 to 1% by mass of alkenyl succinimide or a derivative thereof, and (B) 0.1% by mass of phosphoric ester.
-5% by mass, (C) alkylated diphenylamine is 0.1% by mass.
0.5 to 0.5% by mass and (D) 0.05 to 0.5% by mass of hindered phenols.

The base oil in the present invention is a mineral oil, a synthetic oil, or a mixed oil thereof, and has a kinematic viscosity at 40 ° C. of 10 to 100 mm ² / s, preferably 20 to 85 mm.
² / s, more preferably 30 to 70 mm ² / s, particularly preferably 40 to 60 mm ² / s is suitable. 4
If the kinematic viscosity at 0 ° C. is less than 10 mm ² / s, an appropriate oil film may not be obtained, or the amount of leak may increase,
If it exceeds 100 mm ² / s, the resistance increases. That is, the kinematic viscosity at 40 ° C. is 10 to 100 mm ² / s
If the base oil is out of the range, sufficient pump efficiency cannot be obtained.

Examples of the mineral oil include paraffinic mineral oil, naphthenic mineral oil, intermediate mineral oil, etc. obtained by refining such as solvent refining and hydrorefining, and these may be used alone. And two or more kinds can be used in combination. Further, as the above synthetic oil,
Examples thereof include polybutene and polyolefin copolymers, and these can be used alone or in combination of two or more. Further, in the case of a mixed oil of a mineral oil and a synthetic oil, the above-described mineral oil and the synthetic oil may be combined alone, or two or more mineral oils and the synthetic oil alone may be combined, or conversely, the mineral oil may be combined. A single oil or a combination of two or more oils may be used.

The alkenyl succinimide or a derivative thereof as the component (A) to be blended with the above base oil has a mono-type structure represented by Formula 1 or a bis-type structure represented by Formula 2.

[0010]

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In the formulas (1) and (2), R1 represents a polybutenyl group, and preferably has an average molecular weight of about 1,000 to 1,000.
5000, more preferably about 1000-3000
And particularly preferably about 1000 to 2000. When the average molecular weight of the polybutenyl group is less than 1,000, the effect of dispersing the sludge is low, and the sludge resistance is reduced. When the average molecular weight is more than 5,000, the solubility in the base oil may be reduced. R2 represents a methylene group having 1 to 7 carbon atoms, and a preferable range of the number of carbon atoms is 2 to 5. n is
It represents an integer of 0 to 10, and is preferably an integer of 1 to 7.

The above alkenyl succinimide is generally obtained by reacting polybutenyl succinic anhydride obtained by reacting polybutene with maleic anhydride with a polyamine. Examples of the polyamine to be reacted with polybutenyl succinic anhydride include single diamines such as ethylenediamine, propylenediamine, butylenediamine, and pentylenediamine; diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, and di ( Polyalkylenepolyamines such as methylethylene) triamine, dibutylenetriamine, trifluorobutyltetramine, and pentapentylenehexamine; and the like.

The above alkenyl succinimide derivatives are described in JP-B-42-8013 and JP-B-42-8-13.
No. 014, JP-A-51-52381 and JP-A-51-130.
No. 408, a boron compound derivative of an alkenyl succinimide, an organic phosphonate derivative, in addition to an alkenyl succinimide, an aldehyde,
Alkenyl succinimide derivatives obtained by reacting with ketones, carboxylic acids, sulfonic acids, alkylene oxides, sulfur, polyhydric alcohols, and the like.

The above alkenyl succinimide or a derivative thereof may be used alone, or two or more alkenyl succinimides or two or more derivatives, or a combination of an alkenyl succinimide and a derivative may be used. May be used.

The mixing ratio of the component (A) is 0.01 to 2% by mass, preferably 0.05% by mass of the total mass of the hydraulic oil.
To 2% by mass, more preferably 0.1 to 1.5% by mass, particularly preferably 0.2 to 1.2% by mass. If the component (A) is less than 0.01% by mass, the effect of dispersing the sludge is low, and the sludge resistance is reduced. If it exceeds 2% by mass, the extreme pressure performance is reduced.

The phosphate ester of the component (B) has a structure represented by the following formula (3). In Formula 3, R3 to R5 represent hydrogen or an alkyl group, an alkenyl group, an alkylaryl group, or an arylalkyl group having 1 to 12 carbon atoms;
To R5 may be the same or different. R3-R
When the carbon number of 5 exceeds 12, the solubility in the base oil may decrease. Desirable R3 to R5 are an alkyl group having 3 to 9 carbon atoms.

[0017]

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Examples of the phosphoric acid ester include triaryl phosphate, trialkyl phosphate and the like. Specifically, benzyl diphenyl phosphate,
Allyl diphenyl phosphate, triphenyl phosphate, tricresyl phosphate, ethyl diphenyl phosphate, tributyl phosphate, ethyl dibutyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, ethyl phenyl diphenyl phosphate, diethyl phenyl phenyl phosphate, propyl phenyl diphenyl phosphate, diphenyl Propyl phenyl phenyl phosphate, triethyl phenyl phosphate, tripropyl phenyl phosphate,
Butylphenyl diphenyl phosphate, dibutyl phenyl phenyl phosphate, tributyl phenyl phosphate and the like can be mentioned. These, alone,
Alternatively, two or more kinds can be used in combination.

The compounding ratio of the component (B) is 0.1 to 5% by mass, preferably 0.3 to 3% by mass, more preferably 0.5 to 2% by mass, and particularly preferably 0.5 to 2% by mass of the total mass of the hydraulic oil. Preferably it is 0.7 to 1.5% by mass. If the component (B) is less than 0.1% by mass, sufficient extreme pressure performance cannot be obtained,
Even if it exceeds 5% by mass, the extreme pressure performance is saturated, which is economically disadvantageous.

The alkylated diphenylamine of the component (C) has a structure represented by the following formula (4).

[0021]

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In the formula 4, R6 to R7 are hydrogen or a linear or branched alkyl group having 1 to 16 carbon atoms.
6 to R7 may be the same or different. When the carbon number of the alkyl group exceeds 16, the solubility in oil may be reduced. Preferably, it is a straight-chain or branched-chain alkyl group having 3 to 9 carbon atoms, and more preferably, hydrogen or a straight-chain or branched-chain alkyl group having 4 to 8 carbon atoms.

The straight or branched alkyl group includes
Methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl,
Isopentyl, neopentyl, tert-pentyl, 2
-Methylbutyl, n-hexyl, isohexyl, 3-methylpentyl, ethylbutyl, n-heptyl, 2-methylhexyl, n-octyl, 2-ethylhexyl, 3-
Examples include methylheptyl, n-nonyl, methyloctyl, ethylpeptyl, n-decyl, n-undecyl, n-dodecyl, n-tetradecyl and the like.

Preferred examples of the alkylated diphenylamine as the component (C) include diphenylamine, butyldiphenylamine, octyldiphenylamine, dibutyldiphenylamine, octylbutyldiphenylamine, and dioctyldiphenylamine. They are,
They can be used alone or in combination of two or more.

The compounding ratio of the component (C) is from 0.05 to 0.5% by mass, preferably from 0.05 to 0.5% by mass, based on the total mass of the hydraulic oil.
-0.4 mass%, more preferably 0.1-0.3 mass%, particularly preferably 0.1-0.2 mass%.
If the component (C) is less than 0.05% by mass, sufficient antioxidant performance may not be obtained, and if it exceeds 0.5% by mass, the effect of antioxidant performance is saturated, which is economically disadvantageous. Become.

The hindered phenols of the component (D)
It has a structure represented by Formulas 5, 6, and 7.

[0027]

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In formulas 5 to 7, R8 to R11, R13 to R1
7 represents hydrogen or a linear or branched alkyl group having 1 to 12 carbon atoms, preferably hydrogen or a linear or branched alkyl group having 4 to 8 carbon atoms;
R11 and R13 to R17 may be the same or different. R12 is a methylene group having 1 to 5, preferably 1 to 4 carbon atoms. n is an integer of 1 to 4.

The hindered phenol of the component (D) is
They can be used alone or in combination of two or more.

The mixing ratio of the component (D) is from 0.05 to 0.5% by mass, preferably from 0.1 to 0.5% by mass, based on the total mass of the hydraulic oil.
It is 0.5% by mass, more preferably 0.15 to 0.5% by mass, particularly preferably 0.2 to 0.4% by mass.
If the component (D) is less than 0.05% by mass, sufficient antioxidant performance may not be obtained, and if it exceeds 0.5% by mass, the effect of antioxidant performance is saturated, which is economically disadvantageous. Become.

The hydraulic fluid of the present invention may contain other various additives together with the above components (A) to (D), if necessary. For example, pour point depressants such as styrene-butadiene water-added copolymer, ethylene-propylene copolymer, polyisobutylene and polymethacrylate; defoaming agents such as polyacrylate and polydimethylsiloxane;
Metal deactivators such as benzotriazole and derivatives thereof; demulsifiers such as ethylene oxide-propylene oxide copolymer; and the like.

[0032] The hydraulic oil of the present invention comprises the above (A) to
It can be produced by blending the component (D) and other various additives (hereinafter sometimes simply referred to as each component) with the base oil. The method of mixing the base oil with each component or the method of adding each component to the base oil is not particularly limited, and can be performed by various methods, and the mixing order and the addition order are not particularly limited. For example, each component may be sequentially added to the base oil, or each component may be mixed in advance and added to the base oil.

The hydraulic fluid of the present invention can be used for various hydraulic devices.

[0034]

EXAMPLES In the examples and comparative examples, the following components were blended with the following base oils to prepare hydraulic oils, and the oxidation stability, sludge generation suppression performance, and resistance of each hydraulic oil were adjusted. Sludge performance and extreme pressure performance were evaluated by the following methods.

[Base oil] Highly refined paraffinic mineral oil: A vacuum distilled distillate was subjected to solvent extraction with furfural, solvent dewaxing with methyl ethyl ketone, and further hydrorefining, and a kinematic viscosity at 40 ° C. of 46 mm ² / s. Mineral oil was used.

[Component A] alkenyl succinimide or a derivative thereof: the average molecular weight of the polybutenyl group of R1 is about 1900, R2 is a methylene group having about 2 to 5 carbon atoms, and n
Of about 2 to 6 was used.

[Component B] Phosphate ester: A tricresyl phosphate in which R3 to R5 are the same alkyl group having 7 carbon atoms was used.

[Component C] alkylated diphenylamine:
R6, R7 is hydrogen or -C ₄ straight or branched chain,
Diphenylamine is any combination of H ₉ or -C ₈ H _17, butyl diphenylamine, octyl diphenylamine, di-butyl diphenylamine, octyl butyl diphenylamine, using a mixture of dioctyl diphenylamine.

[D component] Hindered phenols: R1
5, 2,6-di-tert-butyl-p-cresol in which R16 is a tert-butyl group and R17 is a methyl group was used.

[Other additives] Antifoaming agent: dimethylpolysiloxane was used.

[Evaluation Method] (1) The evaluation test of the oxidation stability performance was performed by Cincinnat.
i Milacron Thermal Stabili
TY Test (CM10-SP-7989). That is, the oxidation stability performance test was performed under the following conditions, and the oxidation stability performance was evaluated based on the amount of sludge generated at this time.

The sludge generated is JIS B9931
According to the apparatus (filter pore size: 0.8 μm) and the quantification method described in (Method of measuring hydraulic oil contamination by mass method), sludge generated in the hydraulic oil to be tested is filtered and sludge filtered out Was washed with n-hexane to determine the amount of sludge.

Test conditions: Test temperature: 135 ° C. Test time: 504 hours Sample amount: 200 ml Catalyst: steel rod, copper rod (7.62 mm × 0.635 mm each)
φ)

(2) The evaluation test of the sludge generation suppression performance and the sludge resistance performance was performed using a bench test apparatus including a pump test system (high-pressure piston pump test circuit) shown in FIG. That is, in FIG. 1, a copper catalyst and an iron catalyst are put in the hydraulic oil to be tested poured into the container 1, the hydraulic oil is maintained at a predetermined temperature, the pump is operated, and the hydraulic oil is supplied from the pump to the relief valve to the flow rate. The pressure was circulated in the path from the meter to the oil cooler, and the rise in the differential pressure before and after the relief valve was monitored, and the relief valve was opened and closed to prevent the differential pressure from rising. After the working oil is circulated in the following test conditions in this manner, a predetermined amount is sampled in a state where the generated sludge is uniformly dispersed in the oil after the test, and JIS B99
The amount of sludge was quantified according to 31 devices and a quantification method.

Test conditions: Pump; Uchida Hydraulic product name "A2FO10 piston pump" Relief valve; Uchida Hydraulic product name "DBDH6PA /
400 "Pump pressure; 34.3 MPa Pump rotation speed; 1200 rpm Hydraulic oil flow into container 1; 12 L / min Hydraulic oil temperature in container 1; 80 ° C. Test time (circulation time of hydraulic oil); 1000 hours Test time Hydraulic oil sampling amount after passage: 1000m
l

(3) The extreme pressure evaluation test was performed in accordance with the shell four-ball test (ASTM D2783), and the extreme pressure was evaluated by the wear diameter. The test conditions at this time are shown below.

Test conditions: Rotational speed; 1200 rpm load; 40 kgf Test time; 60 min Test temperature;

Examples 1-2, Comparative Examples 1-3 Base oils and each component were blended in the proportions (% by mass) shown in Tables 1 and 2 to prepare hydraulic oils, and the oxidative stability of these oils was adjusted. The performance, sludge generation suppression performance / sludge resistance performance, and extreme pressure performance were evaluated, and the results are shown in Tables 1 and 2.
In Comparative Example 3, a commercially available mineral oil-based hydraulic oil was used.

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

As described above, in the hydraulic oil of the present invention, the high-temperature and high-pressure of the highly efficient actual piston pump is achieved by the synergistic action of the components (A) to (D) blended into the base oil. Under oxidizing conditions, the composition exhibits excellent oxidation stability, extreme pressure properties, sludge generation suppression properties, and sludge resistance, and can maintain these excellent properties for a long period of time.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an apparatus used for an evaluation test of sludge generation suppression and sludge resistance of a hydraulic fluid of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 133/58 C10M 133/58 137/04 137/04 // C10N 30:04 30:06 30:10 40:08

Claims (1)

[Claims] 1. A hydraulic oil based on mineral oil or synthetic oil or a mixed oil of both, wherein (A) alkenyl succinimide or a derivative thereof is present in an amount of 0.01 to 0.01% based on the total mass of the hydraulic oil. 1% by mass, (B) phosphate ester is 0.1% by mass.
1 to 5% by mass, (C) 0.05 to 0.5% by mass of alkylated diphenylamine, and (D) 0.05 to 0.5% by mass of hindered phenols. hydraulic oil.